Different axes using completely different measurement scales?
Measurement scales are always the same, the units used for display are chosen based on the the length being displayed, eg. you will see 10mm not 0.01m.

The problem you show is from an object that was scaled in object mode. This question can give some more insight into other issues with object scales.

When you have a mesh object and an edge in that mesh is 1 metre long directly along the x axis, the object scale is then applied to the mesh which means it might be visually measured at 0.2 metre in length.

Below you can see a default cube that has been scaled on the y axis in object mode and then scaled again in edit mode. Each edge is the same length as you would expect from a cube, the object scale is then applied to give a very rectangular appearance to the drawn cube.



The solution is to apply the scale to the object while in object mode - CtrlA and select Scale.